Abrasive tool and method of making same



BUCHMANN 2,290,631

ABRASIVE-TOOL AND METHOD OF MAKING SAME I Filed June 17, 1941.

' INVENTOR 100/5 zQ/CHMA/V/V Patented July 2 1, 1942 2,290,631 anaasrvn'roor. AND METHOD or MAKING SAME Louis Buchmann, Bu flalo. N. Y.,assignor to AlnCin, Inc., Buffalo, N. Y.

Application June 17, 1941, Serial No. 398,429

18 Claims.

This invention relates to abrasive tools-and to methods of making thesame. More specifically, the invention relates to an improved method formaking solid metallic tool bodies containing abrasive grains distributedtherethrough and fixed therein in an improved manner.

The invention contemplates a novel and improved method for fabricatingthe metallic body portion or abrasive grain bonding medium thereof, andan improved method of mounting the abrasive grains therewithin.

One object of the present invention is to provide an improved method formounting abrasive granules within a solid metal tool body, whereby theabrasive granules are locked within the tool body in an improved mannerand whereby crushing of the abrasive granules during the mountingprocess is avoided.

Another object of the present invention is to provide an improvedabrasive tool comprising individual abrasive grains and a bonding mediumfor uniting the whole into anintegral structure of improved strength;the abrasive grains being distributed throughout the structure in animproved manner and in accord with a predetermined plan of arrangement.

Another object of the present invention is to provide an improvedabrasive wheel of increased structural strength.

Another object of the present invention is to provide an improved methodof introducing the abrasive granules into the bonding medium duringmanufacture of an abrasive tool.

Another object of the invention is to provide an improved abrasive toolin which the abrasive ingredients thereof are distributed throughout thebody of the tool in accord with any desired plan of varyingconcentration, and in which the abrasive granules are locked within thebody of the tool in an improved manner and are unchanged from the grainsize in which the abrasive granules were originally furnished.

Another object of the invention is to provide an abrasive tool whereinthe abrasive granular ingredients thereof are distributed throughout thebody of the tool in such manner as to expedite and make more economicalthe redressing of the cutting face of the tool subsequent tointermittent use thereof in an improved manner.

. Other objects and advantages of the invention will appear from thespecification herein.

In the drawing:

Fig. 1 is a side elevation of a typical abrasive wheel of the invention;

Fig. 2 is a typical section through the wheel of Fi Fig. 3 is adiagrammatic sectional view through a moldand press apparatusillustrating a step of the fabrication method of the invention; a Fig. 4is a fragmentary section, on an enlarged scale, through a matrix formingelement having mounted thereon abrasive granules preliminary to finalfabrication of a tool of the invention;

Fig. 5 is a side elevation of another form of abrasive carrying wheel ofthe invention;

Fig. 6 is atypical sectional view through the wheel of Fig. 5; and

Fig. 7 is a plan view, on an enlarged scale, of a fragment of afabricating element of the wheel of Figs. 5 and 6, showing the mountingof -abrasive granules thereon in accord with the method of theinvention.

In practicing the invention, the abrasive grits to be employed areunited with a novel form of bonding medium which is made up byassembling in laminated manner sheets of the bonding material. Forexample, as illustrated in Figs. 1-4, a wheel [0 of the invention isshown as comprising a series of discs I l which are formed of sheetmetal disposed in side-by-side relation and pressed and fused togetherto form a unitary.

mass in the desired form of the abrasive wheel. The discs H may beeither of smooth surface form or they may be in the form of deformedsheets; knurled or scratched or acid-etched or otherwise treated toprovide abrasive retaining pockets therein. The metal sheets H arepreferably formed of a metallic substance which is initially relativelysoft and "mushy at temperatures below the fusion point thereof, andreadily weldable and adapted to receive subsequent heat treatments fortempering to desired degrees of hardness and toughness, for purposes aswill be explained hereinafter.

the discs are then arranged in superposed relation and subjected to afusing temperature and then to pressure as provided for by opposed diedevices l5 and I6 (illustrated diagrammatically in Fig. 3). For example,in order to provide the abrasive ingredients of the wheel inconcentrated form in the regions of the most active working portions ofthe wheel, the individual discs going into the make-up of the mostactive working portions of the wheel will preferably be coated withincreased concentrations of abrasive as compared to the discs: goinginto the make-up of the relatively inactive portions of the wheel. Thus,in connection with the manufacture of a V-shaped groove cutting wheel asillustrated in Fig. 2, the center discs II will be initially coated withgreater quantities of abrasive kernels than are the discs at theopposite side portions thereof. The ridge-like peripheral form of thewheel may be obtained either by providing the discs I I of appropriatelydifferent diameters whereby the building up of the laminated structurewill automatically provide the approximate form desired and avoid wasteof expensive abrasive grains, or by using discs of equal diameters ondsubsequently dressing the wheel to desired form following the fusionprocess. Preferably, a temporary binder to hold the abrasive grains inposition to time to cut away surface portions of the tool for reexposureof abrasively active portions thereof. Also, it is most desirable thatthe matrix be not too ductile such as would otherwise permit theabrasive granules to be rolled out of their sockets within the matrix;nor must the matrix be too brittle whereby it would be subject to unduedisintegration under service conditions and the abrasive granules wouldtend to dislodge therefrom priorto full utilization of the abrasioncapacities thereof.

I have found that for the purpose of the invention the disc elements IImay be desirably formed of various grades of carbon steel, or of acopper base alloy containing froma small amount up to 16% aluminum, withor without appreciable addition of other metals such as iron, nickel,and perhaps tin and zinc. For example, a specific alloy which I havefound to be extremely suitable for the purpose is a commerciallyavailable alloy containing approximately 89% copper; 10% aluminum; and1% iron. Such plete volatilization ,under temperatures associ- I atedwith the fusion of the metal sheets and is thus completely eliminated sothat ultimately no other substance remains between the .abrasivegranules and the fused metal.

It is contemplated that various kinds of abrasive granules may beemployed in connection with the method of the invention and that thesizing of the abrasive granules will be regulated as desired and inaccordance with the character of the work to be done by the finishedtool. It

is also contemplated that in connection with the initial deposition ofthe abrasive granules upon the body elements I I any other suitablemeans for accomplishing the desired distribution may be employed, andthat in lieu of lauryl alcohol any other suitable oily or greasy pasteor liquid temporary adhesive substance may be employed, or that theabrasive grains may simply be dusted upon the strip elements without theuse of any carrier substance.

In order to provide the matrix portions of the.

tools of the invention of preferred form, the invention contemplatesusage of a special form of metallic substance which is adapted to beheattreated in a special manner subsequent to fabrication of the toolswhereby the. matrix portions thereof are given improved characteristicsfor the purpose intended. For example, I have found that the discelements II of Figs. 1-4 may, for certain tool purposes, be formed of aninitially soft and temperable steel, or of a suitable member of theso-called copper base alloy group which is adapted to be heat-treated toprovide in the finished product enhanced properties of metal fuses atfrom between 1700 F. to 1900 F.,

depending upon the proportion of the iron content, and thus is wellsuited to the method of 'the invention in connection with thefabrication of abrasive tools employing diamond dust or the like becauseof non-production of deleterious effects upon the abrasive ingredientsat such temperatures. I have found that subsequent to the heating andpressing fabrication method of the invention as-described hereinabove,when employed in connection with the metallic alloy substancesspecified, the fabricated tools may be then heat-treated by heating andquenching in water at from 1500 F. to 1600i F'., followed by temperingat. between .100 F. and 1200 F. Such treatment imparts to the matrixsubstance of the finished tool optimum strength and ductilitycharacteristics which provide a "self dressing" tool adapted to performmost efficiently from the standpoint of utilization of the abrasioncapacities of the abrasive granules disposed within the matrix. Similarsuitable heat treating processes may be applied to the welded tool ofthe invention when fabricated of steel matrix forming elements asexplained hereinabove, for providing the finished product of the desiredgritretaining characteristics. Preferably, the

which are interspersed the abrasive particles in accord with thepredetermined plan of their relative arrangement therein.

A particular feature of the invention resides in that the metalliclaminae for fabrication of the tool are selected so as to be initiallyrelatively soft and adapted to readily soften at temperatures just belowthe temperature of welding so that the abrasive grains may be originallyfurnished of uniform desired size and will then become mounted withinthe body structure of the tool without having been crushed orstructurally weakened during the tool assembly process. Such crushing ofthe abrasive granules between the adjacent metal surfaces will beavoided because of the softness of the metal and the low degree ofpressure needed to be applied to bring the metallic laminae intointimate welding position, Thus, the abrasive granules becomepermanently embedded within the solid coalized pure metallic mass of thetool body, and each abrasive granule is intimately enclosed at all sidesonly by pure metal. Hence, each abrasive granule remains intact asoriginally supplied, and of full dimensions and in structurallyunweakened form whereby the grip of the metallic matrix upon theabrasive granule is of maximum strength and durability.

Thus, the invention clearly distinguishes from and provides markedimprovements and advantages over prior methods for mounting abrasivegranules within metallic holders. For example,

in order to avoid the well known disadvantages and structural weaknessesof sintered tool bodies, a previously customary method for mountingabrasive granules involves minute cutting into the outer surfaces of ametallic body and inlaying abrasive granules intothe cuts so produced,as by pounding or otherwise driving the abrasive therein. Obviously,such methods result in tremendous reduction of abrasive grain size andpulverizing thereof so that the granules become so fractured that theenclosing metal portions cannot cling solidly to the abrasive; whereasthe tool of the present invention entirely avoids such destruction ofthe abrasive granules and encases each grain with a solid pure metalgrip of maximum tenacity.

As illustrated in Figs. 5 and 6, another form of wheel IQ of theinvention is shown as comprising a metallic core around about theperiphery of which has been wound a metallic strip 22 to provide aplurality 'of layers, the number of which depends upon the desired depthof the working portion of the wheel. The

abrasive granules 24 for the wheel are positioned upon the metallicstrip 22 prior to the wrapping of the strip about the core 28 byspreading a supply of the loose granules across the strip 22, and itwill be understood that Fig. 4 also-illustrates the mounting of theabrasive granules 24 anon the base metal elements 22 of the inven- Uponcompletion of the process of winding the strip about the core ill, the'wheel I9 is placed in a-furnace and/or otherwise subjected to anelevated temperature .at. about the degree of initial fusion of themetal of the strip 22 for a length, of time suillcient to providethorough welding of adjacent portions of the grit-carrystrip withoutallowing the bulk, of the metal I thereof to become so fluid as to allowthe impounded abrasive particles to move relative to the mass. Usually,an application of. pressure wheel will be richer in abrasive grit ascompared to the side portions thereof. Consequently, the abrasive gritis employed inaccurately controllable manner; and wasteful employment ofabrasive kernels in the relatively inactive portions of the wheel isavoided thus eiiecting substantial economies whenever the abrasivekernels are of the expensive type" such as diamond dust or the like.Also, it will be seen that because. of the fact that the relatively in-,

tion may he obtained in ways other than hereinabove described inconnection with preparation of the strip 22. For example, a strip ofuniform character may be employed and the abrasive grits may he appliedthereto in any suitable manner so as to give the desired form of graindistribution. For example, the coating of abrasive carrying substance l8which is applied to the strip preparatory to winding thereof about thecore may be applied of increased thickness along the center line of thestrip; or, the strip may be painted by multiple operations involving theapplication of a. mixture along the center line of the strip thatcontains a higher percentage of abrasive to the carrier employed ascompared to the percentage 01' abrasive to the carrier employed inconnection with the painting of the of the strip.

In any case it will be seen that the object is to locate the abrasivekernels in accord with a predetermined desired manner of, distributionthroughout the wheel body by temporarily imnent elements entering intothe assembly of the abrasive wheel and subsequently fusing the upon thestructure during the heating process will also be beneficial and ofassistance in pro- 'viding a thorough welding.

Whenever the stock to be operated upon by the wheel is not initiallyshaped complementary to the shape of the wheel cutting face, thatsection of the wheel that is called upon to do the maincreased number ofgrits per unit of area in the central portion of the strip as'comparedto theside edge portions thereof. Hence, when the strip 22 is woundabout the core 20 and fused.

into place thereon, the central section of the 76 made by fusingxranularmetallic mixtures.

elements thereottogether into a unitary mass of high structural strengthwithout substantially disturbing the distribution and relativeconcentration of the abrasive kernels throughout difl'erent portions ofthe wheel mass;

Thus, the method oi! the invention provides a rugged welded structurewherein the matrix portion thereof is of pure coalized metal form. Thisprovides a tool of greater structural strengthas compared to theso-called "sintered" wheels of the prior art, for example, which are Inthe case of such sintered types of tools the finished products are ofcrystalline-like structural form and resemble in appearance crustymasses of granules adhering to one another by reason only ofintermittent andspace'd points of welded contact, and the masses areusually interspersed with multitudes of minor voids.

Thus, the abrasive grains are at best only partially surrounded by andattached to the'bonding material. Consequently. the finished productsfoif'such prior methods are usually nonuniform as to structural strengthand often contain weak zones which are apt to cause un- Provide a toolthat is made up of a plurality of side edge portions united solidmetallic bodies extending throughout the tool structure; and therefore,even though the fusion process of the method of the present inventionmay not in some instances be carried out to perfection between all ofthe adjacent'surrace portions thereof, the tool will neverthelesshereinforced throughout by the unaltered integral solid metallic bodies.Thus, in no case will the tool of the invention be subject to disruptionunder stress in the manner of sintered wheels, or the like. In the caseof production of tools of the present invention in the form of abrasivewheels as illustrated in the drawing, it will be seen that the laminatedstrip structures Ht-22, upon being welded together provide tools thatare positively reinforced circumi'erentially against centrifugal and/orother forces tending to disrupt them during use.

The avoidance of conditions of fluidity in the metal of the structureduring the fusion process precludes the possibility or redistribution ofthe abrasive grains in the mass and/or undesirable segregation thereofas would otherwise occur under conditions of mass metal fluidity; andthe planned unequal distribution of abrasive particles throughout thewheel mass is accordingly obtained in the finished product. It is ofcourse contemplated that the strip elements l ll22 may be bent or dishedor otherwise deformed in any desired manner before being relativelyassembled so as to provide any desired form of interlocking laminatedstructure.

It will be understood that the invention is applicable with equalfacility to the manufacture of a large variety of abrasive tool shapessuch as are suitable for use in connection with a multiplicity ofindustries, and that although only a limited number of the forms of theinvention have been shown and described in detail herein, variouschanges may be made therein without departing from the spirit of theinvention or the scope of the appended claims,

I claim:

l. The method of fabricating an abrasive tool including the steps ofarranging abrasive granules between metallic sheet material whileholding said abrasive granules in position therebetween in accord with aplan' of irregular distribution to provide a fabrication assembly,heating said metallic material to soften the latter so that saidabrasive granules may press into said metallic material without becomingsubjected to granule-crushing pressures, pressing said assembly togetherwhile heated to metallic softened condition and heat-fusing and pressingthe assembled metallic material and abrasive granules together to form acoalized body of metal with abrasive granules of unchanged formdispersed therethrough and intimately locked therein in accord with saidplan of abrasive ranule distribution.

2. The method of fabricating an abrasive tool including the steps ofapplying lauryl alcohol to surface portions of metallic sheetmaterialand arranging abrasive granules upon said lauryl a1- coholtreated portions of said metallic sheet material for holding saidabrasive granules in posia coalized body of metal with abrasive granulesof unchanged form dispersed therethrough and intimately locked thereinin accord with said plan of abrasive granule distribution.

3. The method of manufacturing an abrasive tool including the steps ofapplying an adhesive substance to surface portions 01 metallic material,mounting abrasive granules upon said applied adhesive substance inaccord with a definite plan of abrasive granule distribution, arrangingsaid metallic material to provide a laminated structure, heating saidmetallic material to soften the latter so that said abrasive granulesmay press thereinto without becoming subjected to granule-crushingpressures, pressing said laminated structure together while heated tometallic material softened condition, and sintering said structure intoa unitary metallic body with said abrasive granules locked by sinteredmetal therein in accord with said definite plan of abrasive granuledistribution, said adhesive substance being of such character as to beeliminated upon sintering of said structure.

a. The method of manufacturing an abrasive tool including the steps ofproviding in association with surface portions of metallic discs meansfor temporarily pocketing in fixed relation thereon abrasive granules inaccord with a definite plan of abrasive granule unequal distributionwhereby the concentration of said granules varies with respect todifferent of said discs, arranging said discs into the form of a single1aminated structure with said abrasive granules temporarily supported bysaid pocketing means therewithin, heating said metallic material tosoften the latter so that said abrasive granules may press thereintowithout becoming subjected to granule-crushing pressures, pressing saidlaminated structure together While heated to metallic material softenedcondition, and fusing the metallic portions of said laminated structuretogether so asto provide a unitary body with said abrasive granuleslocked by said fused metallic portions therewithin in accord with saiddefinite plan of abrasive granule distribution, said granule temporarypocketing means being of such character as to be eliminated upon fusinof said structure.

5. The method of manufacturing an abrasive wheel tool comprising thesteps of applying adhesive substance to a surface portion of a metallicstrip element, pocketing abrasive granules in fixed relation upon saidadhesive substance, said abrasive granules being distributed in accordwith a-definite plan of abrasive granule unequal distribution wherebythe concentration of said granules is reater on one sectiona1 zone ofsaid strip element than on another sectional zone thereof, coiling saidstrip element to provide a wheel structure, heating said metallicmaterial to soften the latter so that said abrasive granules may pressthereinto without becoming subjected to granule-crushing pressures,pressing said laminated structure together while heated to metallicmaterial softened condition, and fusing said wheel structure into aunitary metallic body with said abrasive granules locked by fusedmetaltherein in accord with said definite plan of abrasive granuledistribution, said adhesiv substance being of such character as to bevolatilized and dissipated upon fusing of said structure.

6.: The method of manufacturing an abrasive tool comprising theproviding in association with surface portions of metallic discs meansfor temporarily pocketing in fixed relation thereon abrasive granules inaccord with adefinite plan of abrasivegranule unequal distributionwhereby the concentration of said granules varies with respect todifferent of said discs, arranging said discs into the form of a singlelaminated structure with said abrasive granules temporarily supported bysaid means therewithin, heating said metallic material to soften thlatter so that said abrasive granules may press thereinto withoutbecoming subjected to granule-crushing pressures, pressing saidlaminated structure together while heated to metallic material softenedcondition, and fusing the metallic portions of said laminated structuretogether so as to provide a unitary body with said abrasive granuleslocked by said fused metallic portions therewithin in accord with saiddefinite plan of abrasive granule distribution, said granule temporarypocketing means being of such character as to be volatilized anddissipated upon fusing of said structure.

7. The method of manufacturing an abrasive tool comprising the steps ofarranging in association with a surface portion of a copper-aluminumalloy metallic strip element means for temporarily pocketing in fixedrelation upon said strip element abrasive granules in accord with adefinite plan of abrasive granule unequal distribution whereby theconcentration of said granules is greater in one sectional zone of saidstrip element than in another sectional zone thereof, said granuletemporary pocketing means being of such character as to be eliminatedunder elevated temperature conditions, arranging said abrasive mountingstrip to provide a laminated structure, and fusing said structure into aunitary metallic body with said abrasive granules locked by fused metaltherein in accord with said definite plan of abrasive granuledistribution, and subsequently tempering the metallic structure of thetool by heating and quenching processes.

8. The method of manufacturing an abrasive tool comprising the steps ofproviding in association with surface portions of copper-aluminum alloymetallic laminae means for temporarily pocketing in fixedrelationthereon abrasive granules in accord with a definite plan of abrasivegranule unequal distribution whereby the concentration'of said granulesvaries with respect to different of said laminae, said granule temporarypocketing means being of such characte" as to be eliminated upon fusingof said metallic laminae, arranging said laminae into the form of asingle laminated structure with said abrasive granules temporarilysupported by said means therewithin, and fusing the metallic portions ofsaid laminated structure together so as to provide a. unitary body withsaid'abrasive granules locked by said fused metallic portionstherewithin in accord with said definite plan of abrasive granuledistribution, and subsequently tempering the metallic portion of saidtool by heating and quenching processes.

9. An abrasive tool comprising copper-aluminum ailoy laminae havingabrasive granules pocketed thereon in accord with a definite plan ofunequal distribution, said laminae being fused to provide a coalizedbody, said body having been heat treated for temperingof the metallicalloy content thereof.

10. The method of manufacturing an abrasive tool comprising the steps ofarranging in association with a surface portion of a steel metallicstrip element means for temporarily pocketing in fixed relation uponsaid strip element abrasive granule unequal distribution whereby theconcentration of said granules is greater in one seetional zone of saidstrip element than in another sectional zone thereof, said granuletemporary pocketing means being of such character as to be eliminatedunder elevated temperature conditions, arranging said abrasive mountingstrip to provide a laminated structure, and fusing said structure into aunitary metallic body with said abrasive granules locked by fused metaltherein in accord with said definite plan. of abrasive granuledistribution, and subsequently tempering the metallic structure of thetool by heating and quenching processes.

11. The method of manufacturing an abrasive tool comprising the steps ofproviding in association with surface portions of steel laminae meansfor temporarily pocketing in fixed relation thereon abrasive granules inaccord with a definite plan of abrasive granule unequal distributionwhereby the concentration of said granules varies with respect todifferent of said laminae, said granule temporary pocketing means beingof such character as to be eliminated upon fusing of said metalliclaminae, arranging said laminae into the form of a single laminatedstructure with said abrasive granules temporarily supported by saidmeans therewithin, and fusing the metallic portions of said laminatedstructure together so as to provide a unitary body with said abrasivegranules locked by said fusedmetallic portions therewithin in accordwith. said definite plant of abrasive granule distribution, andsubsequently tempering the metallic portion of said tool by heating andquenching processes.

12. The method of manufacturing an abrasive tool comprising the steps ofarranging in association with a surface portion of a heat temper- -ablestrip element means for temporarily pocketstrip to provide a laminatedstructure, and fusing said structure into a unitary metallic body withsaid abrasive granules locked by fused metaltherein in accord with saiddefinite plan of abrasive granule distribution, and subsequentlytempering the metallic structure of the tool by heating and quenchingprocesses.

13L The method of manufacturmgan abrasive tool comprising the steps ofproviding in association with surface portions of temperable laminaemeans for temporarily pocketing in fixed relation thereon abrasivegranules in' accord with a definite plan of abrasive granule unequaldistribution whereby the concentration of said granules varies withrespect to different of said laminae,

' said granule temporary pocketing means being of such character as tobe eliminated upon fusing of said metallic laminae, arranging saidlaminae into the form of a single laminated structure with said abrasivegranules temporarily supported by said means therewithin, and fusing themetallic portions of said laminated structure together so as to providea unitary body with said abrasive granules locked by said fused metallicportions therewithin in accord with said definite granules in accordwith a definite plan of abrasive 56 plan of abrasive granuledistribution, and subsequently tempering the metallic portion of saidtool by heating and quenching processes.

14. An abrasive tool comprising steel laminae having abrasive granulespocketed thereon in accord with a definite plan of unequal distribution,said laminae being fused to provide a coalized body, said body havingbeen heat treated for tempering of the metallic content thereof.

15. An abrasive tool comprising temper-able metallic laminae havingabrasive granules pocketed thereon in accord with a definite plan ofunequal distribution, said laminae beingiused to provide a coalizedbody, said body having been heat treated for tempering of the metalliccontent thereof.

16. The method of manufacturing an abrasive tool comprising acid etchingsurface portions of metallic laminae to provide pocket means,temporarily pocketing in fixed relation thereon abrasive granules inaccordrwith a definite plan of abrasive granule distribution whereby theconcentration of said granules varies with respect to diflerent of saidlaminae, arranging said laminae into the form of a single laminatedstructure with said abrasive granules temporarily supported by saidpocketing means therewithin, and sintering the metallic portions of saidlaminated structure together so as to provide a unitary body with saidabrasive granules locked by said sintered metallic portions therewithinin accord with said deflnite plan of abrasive granule distribution.

17. The method of manufacturing an abrasive tool comprising applying tosurface portions of metallic laminae lauryl alcohol, temporarilypocketing in fixed relation thereon abrasive granules in accord with adefinite plan of abrasive granule distribution whereby the concentrationof said granules varies with respect to different of said laminae,arranging said laminae into l metallic laminae a volatile substance,temporarily pocketing in fixed relation thereon abrasive granules inaccord with a definite plan of abrasive granule distribution whereby theconcentration of said granules varies with respect to. difierent of saidlaminae, arranging said laminae into the form of a single laminatedstructure with said abrasive granules temporarily supported by saidvolatile substance therewithin, and sintering the metallic portions ofsaid laminated structure together so as to provide a unitary body withsaid abrasive'granules locked by said sintered metallic portionstherewithin in accord with said deflnite plan of abrasive granuledistribution.

LOUIS BUCHNLANN.

